cut -d',' -f1 medals.txt | uniq | wc -l
grep -E '中国,|中国香港,|中国台北,' medals.txt | sort -t',' -k2,2nr -k3,3nr -k4,4nr
sort -t',' -k4,4nr medals.txt | head -n5 | cut -d',' -f1
sort -t',' -k2,2nr medals.txt | head -n5 | awk -F',' '{sum += } END {print sum}'
sort -t"," -k2,2nr medals.txt | head -n5 | awk -F"," "{sum += \$2} END {print sum}"
